My invention relates to an arrangement for digital decoding, and particularly to an arrangement for decoding digital information or data transmitted over a medium that may distort the digital information or data during its transmission.
Digital information or data is being used more frequently and in more applications because of its ability to be transmitted at relatively high speeds and its ability to be recreated after transmission. However, errors can occur in the digital information when the communication medium becomes relatively noisy, as it may in radio and wire systems; or where the communication medium is subject to fast fading, such as in mobile radio systems. Because of this, digital information is frequently transmitted a plurality of times to insure reliable and accurate reception. One well known system transmits each digital signal three times, either in direct sequence, or in digital words which are transmitted three times. At the receiving end, the digital signals are detected, and a majority vote is taken on each of the correponding three digital signals. In the case of binary signals, if three logic 1's or if two logic 1's and one logic 0 are received, then a decision is made that a logic 1 was received. On the other hand, if three logic 0's or if two logic 0's and one logic 1 are received, then a decision is made that a logic 0 was received. This system is fairly accurate, as its decision is based on at least two out of three repeated digital signals being the same.
While such a system works well, and provides relatively reliable and accurate signals, such a system requires that each digital signal be transmitted at least three times. Such a requirement utilizes a relatively valuable communication medium for a relatively long length of time, since each digital message must be transmitted three times in sequence. Accordingly, there is a need for a digital decoding arrangement that is reliable and accurate, and that reduces the required time for transmitting the digital signals over a communication medium.